package com.chen; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.AbstractQueuedSynchronizer; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; /**  * desc：自定义同步组件，只允许最多n个线程同时访问  * // 1.共享访问  * // 2.定义n个资源数  * Created by chenjianye on 2017/5/26.  */ public class ServerLock implements Lock{
      private Sync sync = null;     public ServerLock(int ServerLockNum) {
          this.sync = new Sync(ServerLockNum);     }     private final class Sync extends AbstractQueuedSynchronizer {
          Sync(int count){
              setState(count);         }         public int tryAcquireShared(int reduceCount) {
              for(;;) {
                  int current = getState();                 int newCount = current - reduceCount;                 if (newCount < 0 || compareAndSetState(current, newCount)) {
                      return newCount;                 }             }         }         public boolean tryReleaseShared(int returnCount) {
              for(;;) {
                  int current = getState();                 int newCount = current + returnCount;                 if (compareAndSetState(current, newCount)) {
                      return true;                 }             }         }     }     @Override     public void lock() {
  //        sync.acquire(1);         sync.acquireShared(1);     }     @Override     public void unlock() {
          sync.releaseShared(1);     }     @Override     public void lockInterruptibly() throws InterruptedException {
          System.out.println("dd");     }     @Override     public boolean tryLock() {
          return false;     }     @Override     public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
          return sync.tryAcquireNanos(1, unit.toNanos(1000));     }     @Override     public Condition newCondition() {
          throw new RuntimeException("");     } }

package com.chen; import java.util.concurrent.locks.Lock; /**  * desc：测试自定义锁  * Created by chenjianye on 2017/5/26.  */ public class TestLock {
      public static void main(String[] args) {
          ServerLock lock = new ServerLock(4); //        ReentrantReadWriteLock lock = new ReentrantReadWriteLock(); //        Lock tmp = lock.writeLock();         for(int i=0;i<20;i++) {
              Worker worker = new Worker(lock);             worker.start();         }     }     static class Worker extends Thread{
          Lock lock;         Worker(Lock lock) {
              this.lock = lock;         }         public void run() {
              while (true) {
                  lock.lock();                 try{
                      Thread.sleep(1000);                     System.out.println("Thread name:" + Thread.currentThread().getName()+"时间："+System.currentTimeMillis()/1000);                 } catch (InterruptedException e) {
                      e.printStackTrace();                 } finally {
                      lock.unlock();                 }             }         }     } }